class AsyncFromStream<T>

undocumented

Extends: AsyncStreamBase<T>

Type parameters

Name	Description
T	undocumented

Properties

[Symbol.asyncIterator]

undocumented

Definition

[Symbol.asyncIterator]: () => AsyncFastIterator<T>;

Methods

[Symbol.asyncIterator]

undocumented

Definition

abstract [Symbol.asyncIterator](): AsyncFastIterator<T>;

Overrides

AsyncFastIterable.[Symbol.asyncIterator], AsyncStreamBase.[Symbol.asyncIterator]

append

Returns the current stream succeeded by the given value

Definition

append(value: AsyncOptLazy<T>): AsyncStream.NonEmpty<T>;

Parameters

Name	Type	Description
value	AsyncOptLazy<T>

example

await AsyncStream.of(1, 2, 3).append(4).toArray()
// => [1, 2, 3, 4]

note

O(1)

Overrides

AsyncStream.append, AsyncStreamBase.append

asNormal

undocumented

Definition

asNormal(): AsyncStream<T>;

Overrides

AsyncStreamBase.asNormal

assumeNonEmpty

Returns the stream as a non-empty instance.

Definition

assumeNonEmpty(): AsyncStream.NonEmpty<T>;

throws

RimbuError.EmptyCollectionAssumedNonEmptyError if the stream is known to be empty.

example

AsyncStream.from(Stream.range({ amount: 100 })).assumeNonEmpty()
// => type: AsyncStream.NonEmpty<number>

note

the function does not actually check if the stream is empty, so treat with extra care @note O(1)

Overrides

AsyncStream.assumeNonEmpty, AsyncStreamBase.assumeNonEmpty

asyncStream

Returns an async stream of elements of type T.

Definition

asyncStream(): this;

example

AsyncStream.of(1, 2, 3).asyncStream()
// => returns itself

Overrides

AsyncStream.asyncStream, AsyncStreamBase.asyncStream

collect

Returns an AsyncStream containing the resulting elements from applying the given collectFun to each element in this Stream.

Definition

collect<R>(collectFun: AsyncCollectFun<T, R>): AsyncStream<R>;

Type parameters

Name	Description
R

Parameters

Name	Type	Description
collectFun	AsyncCollectFun<T, R>

example

await AsyncStream.of(1, 2, 3).collect(async (v, i, skip, halt) => {
if (i === 0) return skip;
if (i === 1) halt();
return String(v)
}).toArray();
// => ['1']

note

O(1)

Overrides

AsyncStream.collect, AsyncStreamBase.collect

concat

Returns an AsyncStream containing the elements of this stream followed by all elements produced by the others array of AsyncStreamSources.

Definition

concat(...others: ArrayNonEmpty<AsyncStreamSource<T>>): any;

Parameters

Name	Type	Description
others	ArrayNonEmpty<AsyncStreamSource<T>>

example

await AsyncStream.of(1, 2, 3).concat([4, 5], () => [6, 7]).toArray()
// [1, 2, 3, 4, 5, 6, 7]

note

O(1)

Overrides

AsyncStream.concat, AsyncStreamBase.concat

contains

Returns true if the AsyncStream contains given amount instances of given value, using given eq function.

Definition

contains(searchValue: T, options?: {
    amount?: number;
    eq?: Eq<T>;
    negate?: boolean;
  }): Promise<boolean>;

Parameters

Name	Type	Description
searchValue	T
options	{     amount?: number;     eq?: Eq<T>;     negate?: boolean;   }

example

const source = Stream.from('marmot')
await source.contains('m')    // => true
await source.contains('m', 2) // => true
await source.contains('m', 3) // => false
await source.contains('q')    // => false

note

O(N)

Overrides

AsyncStream.contains, AsyncStreamBase.contains

containsSlice

Returns true if this stream contains the same sequence of elements as the given source, false otherwise.

Definition

containsSlice(source: AsyncStreamSource.NonEmpty<T>, options?: {
    eq?: Eq<T>;
    amount?: number;
  }): Promise<boolean>;

Parameters

Name	Type	Description
source	AsyncStreamSource.NonEmpty<T>
options	{     eq?: Eq<T>;     amount?: number;   }

example

await AsyncStream.of(1, 2, 3, 4, 5).containsSlice([2, 3, 4])
// => true
await AsyncStream.of(1, 2, 3, 4, 5).containsSlice([4, 3, 2])
// => false

Overrides

AsyncStream.containsSlice, AsyncStreamBase.containsSlice

count

Returns the amount of elements in the AsyncStream.

Definition

count(): Promise<number>;

example

await AsyncStream.of(1, 2, 3).count() // => 3

note

O(N) for most types of Stream @note be careful not to use on infinite streams

Overrides

AsyncStream.count, AsyncStreamBase.count

countElement

Returns the amount of elements that are equal according to the given eq to the given value in the AsyncStream.

Definition

countElement(value: T, options?: {
    eq?: Eq<T>;
    negate?: boolean;
  }): Promise<number>;

Parameters

Name	Type	Description
value	T
options	{     eq?: Eq<T>;     negate?: boolean;   }

example

await AsyncStream.of(1, 2, 3).countElement(2) // => 1
await AsyncStream.of(1, 2, 3).countElement(2, { negate: true }) // => 2

note

O(N) @note be careful not to use on infinite streams

Overrides

AsyncStream.countElement, AsyncStreamBase.countElement

distinctPrevious

Returns an AsyncStream containing non-repetitive elements of the source stream, where repetitive elements are compared using the optionally given eq equality function.

Definition

distinctPrevious(options?: {
    eq?: Eq<T> | undefined;
    negate?: boolean | undefined;
  }): AsyncStream<T>;

Parameters

Name	Type	Description
options	{     eq?: Eq<T> | undefined;     negate?: boolean | undefined;   }

example

await AsyncStream.of(1, 1, 2, 2, 3, 1).distinctPrevious().toArray()
// => [1, 2, 3, 1]

Overrides

AsyncStream.distinctPrevious, AsyncStreamBase.distinctPrevious

drop

Returns an AsyncStream that skips the first amount elements of this stream and returns the rest.

Definition

drop(amount: number): AsyncStream<T>;

Parameters

Name	Type	Description
amount	number

example

await AsyncStream.of(1, 2, 3).drop(1).toArray()   // => [2, 3]

note

O(N)

Overrides

AsyncStream.drop, AsyncStreamBase.drop

dropWhile

Returns an AsyncStream that contains the elements of this stream starting from the first element that does not satisfy given pred function.

Definition

dropWhile(pred: (value: T, index: number) => MaybePromise<boolean>, options?: {
    negate?: boolean;
  }): AsyncStream<T>;

Parameters

Name	Type	Description
pred	(value: T, index: number) => MaybePromise<boolean>
options	{     negate?: boolean;   }

example

await AsyncStream.of(1, 2, 3).dropWhile(async v => v < 2).toArray()
// => [2, 3]

note

O(N)

Overrides

AsyncStream.dropWhile, AsyncStreamBase.dropWhile

elementAt

Returns the element in the AsyncStream at the given index, or a fallback value (default undefined) otherwise.

Definition

elementAt<O>(index: number, otherwise?: AsyncOptLazy<O>): Promise<T | O>;

Type parameters

Name	Description
O

Parameters

Name	Type	Description
index	number
otherwise	AsyncOptLazy<O>

example

await AsyncStream.of(1, 2, 3).elementAt(1)        // => 2
await AsyncStream.of(1, 2, 3).elementAt(5)        // => undefined
await AsyncStream.of(1, 2, 3).elementAt(5, 'a')   // => 'a'
await AsyncStream.of(1, 2, 3).elementAt(5, async () => 'a')   // => 'a'

note

O(N) for most types of Stream

Overrides

AsyncStream.elementAt, AsyncStreamBase.elementAt

equals

Returns true if the sequence of elements in this stream are equal to the sequence in the other stream according to the provided eq function.

Definition

equals(other: AsyncStreamSource<T>, options?: {
    eq?: Eq<T>;
    negate?: boolean;
  }): Promise<boolean>;

Parameters

Name	Type	Description
other	AsyncStreamSource<T>
options	{     eq?: Eq<T>;     negate?: boolean;   }

example

await AsyncStream.of(1, 2, 3).equals([1, 2, 3])     // => true
await AsyncStream.of(1, 2, 3, 4).equals([1, 2, 3])  // => false

note

don't use on potentially infinite streams @note O(N)

Overrides

AsyncStream.equals, AsyncStreamBase.equals

every

Returns true if every element of the AsyncStream satifies given pred function.

Definition

every(pred: (value: T, index: number) => MaybePromise<boolean>, options?: {
    negate?: boolean;
  }): Promise<boolean>;

Parameters

Name	Type	Description
pred	(value: T, index: number) => MaybePromise<boolean>
options	{     negate?: boolean;   }

example

await AsyncStream.of(1, 2, 3).every((v, i) => v + i > 10)  // => false
await AsyncStream.of(1, 2, 3).every(async (v, i) => v + i < 10)  // => true

note

O(N)

Overrides

AsyncStream.every, AsyncStreamBase.every

filter

Returns an AsyncStream containing only those elements from this stream for which the given pred function returns true.

Definition

filter(pred: (value: T, index: number, halt: () => void) => MaybePromise<boolean>, options?: {
    negate?: boolean | undefined;
  }): any;

Parameters

Name	Type	Description
pred	(value: T, index: number, halt: () => void) => MaybePromise<boolean>
options	{     negate?: boolean | undefined;   }

note

if the predicate is a type guard, the return type is automatically inferred @note O(1)

example

await AsyncStream.of(1, 2, 3).filter(async (v, i) => v + i !== 3).toArray()
// => [1, 3]
await AsyncStream.of(1, 2, 3).filter(async (v, i) => v + i !== 3, { negate: true }).toArray()
// => [2]

Overrides

AsyncStream.filter, AsyncStreamBase.filter

filterPure

Returns an AsyncStream containing only those elements from this stream for which the given pred function returns true.

Definition

filterPure<A extends readonly unknown[]>(options: {
    pred: (value: T, ...args: A) => MaybePromise<boolean>;
    negate?: boolean | undefined;
  }, ...args: A): any;

Type parameters

Name	Constraints	Description
A	readonly unknown[]

Parameters

Name	Type	Description
options	{     pred: (value: T, ...args: A) => MaybePromise<boolean>;     negate?: boolean | undefined;   }
args	A

note

if the predicate is a type guard, the return type is automatically inferred @note O(1)

example

await AsyncStream.of(1, 2, 3).filterPure({ pred: Object.is }, 2).toArray()
// => [2]
await AsyncStream.of(1, 2, 3).filterPure({ pred: Object.is, negate: true }, 2).toArray()
// => [1, 3]

Overrides

AsyncStream.filterPure, AsyncStreamBase.filterPure

find

Returns the first element for which the given pred function returns true, or a fallback value otherwise.

Definition

find<O>(pred: (value: T, index: number) => MaybePromise<boolean>, options?: {
    occurrance?: number | undefined;
    negate?: boolean | undefined;
    otherwise?: AsyncOptLazy<O>;
  }): Promise<T | O>;

Type parameters

Name	Description
O

Parameters

Name	Type	Description
pred	(value: T, index: number) => MaybePromise<boolean>
options	{     occurrance?: number | undefined;     negate?: boolean | undefined;     otherwise?: AsyncOptLazy<O>;   }

note

if the predicate is a type guard, the return type is automatically inferred

example

const isEven = async (v: number) => v % 2 === 0
await AsyncStream.of(1, 2, 3, 4).find(isEven)           // => 2
await AsyncStream.of(1, 2, 3, 4).find(isEven, { occurrance: 2 })        // => 4
await AsyncStream.of(1, 2, 3, 4).find(isEven, { occurrance: 3 })        // => undefined
await AsyncStream.of(1, 2, 3, 4).find(isEven, { occurrance: 3, otherwise: 'a' })
// => 'a'

note

O(N)

Overrides

AsyncStream.find, AsyncStreamBase.find

first

Returns the first element of the AsyncStream, or a fallback value (default undefined) if the stream is empty.

Definition

first<O>(otherwise?: AsyncOptLazy<O>): Promise<T | O>;

Type parameters

Name	Description
O

Parameters

Name	Type	Description
otherwise	AsyncOptLazy<O>

example

await AsyncStream.of(1, 2, 3).first()      // => 1
await AsyncStream.empty<number>().first()  // => undefined
await AsyncStream.empty<number>().first(0) // => 0
await AsyncStream.empty<number>().first(async () => 0) // => 0

note

O(1)

Overrides

AsyncStream.first, AsyncStreamBase.first

flatMap

Returns an AsyncStream consisting of the concatenation of flatMapFun applied to each element.

Definition

flatMap<T2>(flatMapFun: (value: T, index: number, halt: () => void) => AsyncStreamSource<T2>): AsyncStream<T2>;

Type parameters

Name	Description
T2

Parameters

Name	Type	Description
flatMapFun	(value: T, index: number, halt: () => void) => AsyncStreamSource<T2>

note

O(1)

example

await AsyncStream.of(1, 2, 3).flatMap(async (v, i, halt) => {
if (i >= 1) halt();
return [v, i, v + i]
}).toArray()
// => [1, 0, 1, 2, 1, 3]

Overrides

AsyncStream.flatMap, AsyncStreamBase.flatMap

flatZip

Returns an AsyncStream consisting of the concatenation of flatMapFun applied to each element, zipped with the element that was provided to the function.

Definition

flatZip<T2>(flatMapFun: (value: T, index: number, halt: () => void) => AsyncStreamSource<T2>): AsyncStream<[T, T2]>;

Type parameters

Name	Description
T2

Parameters

Name	Type	Description
flatMapFun	(value: T, index: number, halt: () => void) => AsyncStreamSource<T2>

note

O(1)

example

await AsyncStream.of(1, 2, 3).flatZip((v, i, halt) => {
if (i >= 1) halt();
return [v, i, v + i]
}).toArray()
// => [[1, 1], [1, 0], [1, 1], [2, 2], [2, 1], [2, 3]]

Overrides

AsyncStream.flatZip, AsyncStreamBase.flatZip

fold

Returns the value resulting from applying the given the given next function to a current state (initially the given init value), and the next stream value, and returning the new state. When all elements are processed, the resulting state is returned.

Definition

fold<R>(init: AsyncOptLazy<R>, next: (current: R, value: T, index: number, halt: () => void) => MaybePromise<R>): Promise<R>;

Type parameters

Name	Description
R

Parameters

Name	Type	Description
init	AsyncOptLazy<R>
next	(current: R, value: T, index: number, halt: () => void) => MaybePromise<R>

example

console.log(await AsyncStream.empty<number>().fold(5, async (current, value) => current + value))
// => 5
console.log(await AsyncStream.of(1, 2, 3).fold(() => 5, (current, value) => current + value))
// => 11  (= 5 + 1 + 2 + 3)

Overrides

AsyncStream.fold, AsyncStreamBase.fold

foldStream

Returns an AsyncStream containing the values resulting from applying the given the given next function to a current state (initially the given init value), and the next stream value, and returning the new state.

Definition

foldStream<R>(init: AsyncOptLazy<R>, next: (current: R, value: T, index: number, halt: () => void) => MaybePromise<R>): AsyncStream<R>;

Type parameters

Name	Description
R

Parameters

Name	Type	Description
init	AsyncOptLazy<R>
next	(current: R, value: T, index: number, halt: () => void) => MaybePromise<R>

example

console.log(
await AsyncStream.empty<number>()
.foldStream(5, async (current, value) => current + value)
.toArray()
)
// => []
console.log(
await AsyncStream.of(1, 2, 3)
.foldStream(() => 5, (current, value) => current + value)
.toArray()
)
// => [6, 8, 11]

Overrides

AsyncStream.foldStream, AsyncStreamBase.foldStream

forEach

Performs given function f for each element of the Stream, using given state as initial traversal state.

Definition

forEach(f: (value: T, index: number, halt: () => void) => MaybePromise<void>, options?: {
    state?: TraverseState;
  }): Promise<void>;

Parameters

Name	Type	Description
f	(value: T, index: number, halt: () => void) => MaybePromise<void>
options	{     state?: TraverseState;   }

note

if f is an async function, each call will be awaited consecutively

example

await AsyncStream.of(1, 2, 3).forEach(async (v, i, halt) => {
console.log(v);
if (i >= 1) halt();
})
// => 1, 2

note

O(N)

Overrides

AsyncStream.forEach, AsyncStreamBase.forEach

forEachPure

Performs given function f for each element of the Stream, with the optionally given args as extra arguments.

Definition

forEachPure<A extends readonly unknown[]>(f: (value: T, ...args: A) => MaybePromise<void>, ...args: A): Promise<void>;

Type parameters

Name	Constraints	Description
A	readonly unknown[]

Parameters

Name	Type	Description
f	(value: T, ...args: A) => MaybePromise<void>
args	A

note

if f is an async function, each call will be awaited consecutively

example

await AsyncStream.of(1, 2, 3).forEachPure(console.log, 'sheep')
// => logs:
// 1 sheep
// 2 sheep
// 3 sheep

note

O(N)

Overrides

AsyncStream.forEachPure, AsyncStreamBase.forEachPure

groupBy

Returns a promise resolving to the result of applying the valueToKey function to calculate a key for each value, and feeding the tuple of the key and the value to the collector reducer, and finally returning its result. If no collector is given, the default collector will return a JS multimap of the type Map<K, V[]>.

Definition

groupBy<K, R>(valueToKey: (value: T, index: number) => MaybePromise<K>, options?: {
    collector?: AsyncReducer.Accept<readonly [K, T], R> | undefined;
  }): Promise<R>;

Type parameters

Name	Description
K
R

Parameters

Name	Type	Description
valueToKey	(value: T, index: number) => MaybePromise<K>
options	{     collector?: AsyncReducer.Accept<readonly [K, T], R> | undefined;   }

example

await AsyncStream.of(1, 2, 3).groupBy((v) => v % 2)
// => Map {0 => [2], 1 => [1, 3]}

Overrides

AsyncStream.groupBy, AsyncStreamBase.groupBy

indexed

Returns an AsyncStream where each element in this stream is paired with its index

Definition

indexed(options?: {
    startIndex?: number;
  }): AsyncStream<[number, T]>;

Parameters

Name	Type	Description
options	{     startIndex?: number;   }

example

await AsyncStream.of(1, 2, 3).indexed().toArray()
// => [[0, 1], [1, 2], [2, 3]]

note

O(1)

Overrides

AsyncStream.indexed, AsyncStreamBase.indexed

indexOf

Returns the index of the occurrance instance of given searchValue in the AsyncStream, using given eq function, or undefined if no such value is found.

Definition

indexOf(searchValue: T, options?: {
    occurrance?: number | undefined;
    eq?: Eq<T> | undefined;
    negate?: boolean | undefined;
  }): Promise<number | undefined>;

Parameters

Name	Type	Description
searchValue	T
options	{     occurrance?: number | undefined;     eq?: Eq<T> | undefined;     negate?: boolean | undefined;   }

example

const source = AsyncStream.from('marmot')
await source.indexOf('m')     // => 0
await source.indexOf('m', { occurrance: 2 })  // => 3
await source.indexOf('m', { occurrance: 3 })  // => undefined
await source.indexOf('q')     // => undefined

note

O(N)

Overrides

AsyncStream.indexOf, AsyncStreamBase.indexOf

indexWhere

Returns the index of the given occurrance instance of the element in the AsyncStream that satisfies given pred function, or undefined if no such instance is found.

Definition

indexWhere(pred: (value: T, index: number) => MaybePromise<boolean>, options?: {
    occurrance?: number;
    negate?: boolean;
  }): Promise<number | undefined>;

Parameters

Name	Type	Description
pred	(value: T, index: number) => MaybePromise<boolean>
options	{     occurrance?: number;     negate?: boolean;   }

example

await AsyncStream.of(1, 2, 3).indexWhere((v, i) => v + i > 2)      // => 1
await AsyncStream.of(1, 2, 3).indexWhere(async (v, i) => v + i > 2, { occurrance: 2 })   // => 2

note

O(N)

Overrides

AsyncStream.indexWhere, AsyncStreamBase.indexWhere

indicesOf

Returns an AsyncStream containing the indicies of the occurrance of the given searchValue, according to given eq function.

Definition

indicesOf(searchValue: T, options?: {
    eq?: Eq<T>;
    negate?: boolean;
  }): AsyncStream<number>;

Parameters

Name	Type	Description
searchValue	T
options	{     eq?: Eq<T>;     negate?: boolean;   }

example

await AsyncStream.from('marmot').indicesOf('m').toArray()
// => [0, 3]

note

O(N)

Overrides

AsyncStream.indicesOf, AsyncStreamBase.indicesOf

indicesWhere

Returns an AsyncStream containing the indices of the elements for which the given pred function returns true.

Definition

indicesWhere(pred: (value: T) => MaybePromise<boolean>, options?: {
    negate?: boolean;
  }): AsyncStream<number>;

Parameters

Name	Type	Description
pred	(value: T) => MaybePromise<boolean>
options	{     negate?: boolean;   }

example

await AsyncStream.of(1, 2, 3).indicesWhere((v, i) => v + i !== 3).toArray()
// => [0, 2]

note

O(N)

Overrides

AsyncStream.indicesWhere, AsyncStreamBase.indicesWhere

intersperse

Returns an AsyncStream with all elements from the given sep AsyncStreamSource between two elements of this stream.

Definition

intersperse(sep: AsyncStreamSource<T>): AsyncStream<T>;

Parameters

Name	Type	Description
sep	AsyncStreamSource<T>

example

await AsyncStream.of(1, 2, 3).intersperse("ab").toArray()
// => [1, 'a', 'b', 2, 'a', 'b', 3]

note

O(1)

Overrides

AsyncStream.intersperse, AsyncStreamBase.intersperse

join

Returns a string resulting from converting each element to string with options.valueToString, interspersed with options.sep, starting with options.start and ending with options.end.

Definition

join({ sep, start, end, valueToString, ifEmpty, }?: {
    sep?: string | undefined;
    start?: string | undefined;
    end?: string | undefined;
    valueToString?: StringConstructor | undefined;
    ifEmpty?: undefined;
  }): Promise<string>;

Parameters

Name	Type	Description
{ sep, start, end, valueToString, ifEmpty, }	{     sep?: string | undefined;     start?: string | undefined;     end?: string | undefined;     valueToString?: StringConstructor | undefined;     ifEmpty?: undefined;   }

example

await AsyncStream.of(1, 2, 3).join({ start: '<', sep: ', ', end: '>' })
// => '<1, 2, 3>'

note

O(N)

Overrides

AsyncStream.join, AsyncStreamBase.join

last

Returns the last element of the AsyncStream, or a fallback value (default undefined) if the stream is empty.

Definition

last<O>(otherwise?: AsyncOptLazy<O>): Promise<T | O>;

Type parameters

Name	Description
O

Parameters

Name	Type	Description
otherwise	AsyncOptLazy<O>

example

await AsyncStream.of(1, 2, 3).last()      // => 3
await AsyncStream.empty<number>().last()  // => undefined
await AsyncStream.empty<number>().last(0) // => 0
await AsyncStream.empty<number>().last(async () => 0) // => 0

note

O(N)

Overrides

AsyncStream.last, AsyncStreamBase.last

map

Returns an AsyncStream where mapFun is applied to each element.

Definition

map<T2>(mapFun: (value: T, index: number) => MaybePromise<T2>): AsyncStream<T2>;

Type parameters

Name	Description
T2

Parameters

Name	Type	Description
mapFun	(value: T, index: number) => MaybePromise<T2>

example

await AsyncStream.of(1, 2, 3).map(async (v, i) => `[${i}]: ${v}`).toArray()
// => ['[0]: 1', '[1]: 2', '[2]: 3']

note

O(1)

Overrides

AsyncStream.map, AsyncStreamBase.map

mapPure

Returns an AsyncStream where the given mapFun is applied to each value in the stream, with optionally as extra arguments the given args.

Definition

mapPure<T2, A extends readonly unknown[]>(mapFun: (value: T, ...args: A) => MaybePromise<T2>, ...args: A): AsyncStream<T2>;

Type parameters

Name	Constraints	Description
T2
A	readonly unknown[]

Parameters

Name	Type	Description
mapFun	(value: T, ...args: A) => MaybePromise<T2>
args	A

note

is mostly aimed to increase performance so that an extra function is not required @note can be used on function that really expect 1 argument, since the normal map will also pass more arguments

example

const s = AsyncStream.of({ a: 1 }, { a: 2, c: { d: true } })
const s2 = s.mapPure(JSON.stringify, ['a'], 5)
// when stream is evaluated, will call JSON.stringify on each stream element with the given extra arguments
console.log(await s2.toArray())
// => ["{\n \"a\": 1\n}", "{\n \"a\": 2\n}"]

Overrides

AsyncStream.mapPure, AsyncStreamBase.mapPure

max

Returns the maximum element of the AsyncStream according to a default compare function, or the provided otherwise fallback value if the stream is empty.

Definition

max<O>(otherwise?: AsyncOptLazy<O>): Promise<T | O>;

Type parameters

Name	Description
O

Parameters

Name	Type	Description
otherwise	AsyncOptLazy<O>

example

await AsyncStream.of(5, 1, 3).max()         // => 5
await AsyncStream.empty<number>().max()     // => undefined
await AsyncStream.empty<number>().max('a')  // => 'a'

note

O(N)

Overrides

AsyncStream.max, AsyncStreamBase.max

maxBy

Returns the maximum element of the AsyncStream according to the provided compare function, or the provided otherwise fallback value if the stream is empty.

Definition

maxBy<O>(compare: (v1: T, v2: T) => number, otherwise?: AsyncOptLazy<O>): Promise<T | O>;

Type parameters

Name	Description
O

Parameters

Name	Type	Description
compare	(v1: T, v2: T) => number
otherwise	AsyncOptLazy<O>

example

function compareLength(a: string, b: string): number { return b.length - a.length };
await AsyncStream.of('abc', 'a', 'ab').maxBy(compareLength)   // => 'abc'
await AsyncStream.empty<string>().maxBy(compareLength)        // => undefined
await AsyncStream.empty<string>().maxBy(compareLength, 'a')   // => 'a'

note

O(N)

Overrides

AsyncStream.maxBy, AsyncStreamBase.maxBy

min

Returns the mimimum element of the AsyncStream according to a default compare function, or the provided otherwise fallback value if the stream is empty.

Definition

min<O>(otherwise?: AsyncOptLazy<O>): Promise<T | O>;

Type parameters

Name	Description
O

Parameters

Name	Type	Description
otherwise	AsyncOptLazy<O>

example

await AsyncStream.of(5, 1, 3).min()         // => 1
await AsyncStream.empty<number>().min()     // => undefined
await AsyncStream.empty<number>().min('a')  // => 'a'
await AsyncStream.empty<number>().min(async () => 'a')  // => 'a'

note

O(N)

Overrides

AsyncStream.min, AsyncStreamBase.min

minBy

Returns the mimimum element of the AsyncStream according to the provided compare function, or the provided otherwise fallback value if the stream is empty.

Definition

minBy<O>(compare: (v1: T, v2: T) => number, otherwise?: AsyncOptLazy<O>): Promise<T | O>;

Type parameters

Name	Description
O

Parameters

Name	Type	Description
compare	(v1: T, v2: T) => number
otherwise	AsyncOptLazy<O>

example

function compareLength(a: string, b: string): number { return b.length - a.length };
await AsyncStream.of('abc', 'a', 'ab').minBy(compareLength)   // => 'a'
await AsyncStream.empty<string>().minBy(compareLength)        // => undefined
await AsyncStream.empty<string>().minBy(compareLength, 'a')   // => 'a'

note

O(N)

Overrides

AsyncStream.minBy, AsyncStreamBase.minBy

mkGroup

Returns an AsyncStream starting with options.sep, then returning the elements of this Stream interspersed with options.sep, and ending with options.end.

Definition

mkGroup({ sep, start, end, }?: {
    sep?: AsyncStreamSource<T>;
    start?: AsyncStreamSource<T>;
    end?: AsyncStreamSource<T>;
  }): any;

Parameters

Name	Type	Description
{ sep, start, end, }	{     sep?: AsyncStreamSource<T>;     start?: AsyncStreamSource<T>;     end?: AsyncStreamSource<T>;   }

example

await AsyncStream.of(1, 2, 3).mkGroup({ start: '<<', sep: '-', end: '>>' }).toArray()
// => ['<', '<', 1, '-', 2, '-', 3, '>', '>']

note

O(N)

Overrides

AsyncStream.mkGroup, AsyncStreamBase.mkGroup

partition

Returns a promise resolving to a tuple of which the first element is the result of collecting the elements for which the given predicate is true, and the second one the result of collecting the other elements. Own reducers can be provided as collectors, by default the values are collected into an array.

Definition

partition(pred: (value: T, index: number) => MaybePromise<boolean>, options?: {
    collectorTrue?: any;
    collectorFalse?: any;
  }): Promise<[any, any]>;

Parameters

Name	Type	Description
pred	(value: T, index: number) => MaybePromise<boolean>
options	{     collectorTrue?: any;     collectorFalse?: any;   }

note

if the predicate is a type guard, the return type is automatically inferred

Overrides

AsyncStream.partition, AsyncStreamBase.partition

prepend

Returns the current stream preceded by the given value

Definition

prepend(value: AsyncOptLazy<T>): AsyncStream.NonEmpty<T>;

Parameters

Name	Type	Description
value	AsyncOptLazy<T>

example

await AsyncStream.of(1, 2, 3).prepend(0).toArray()
// => [0, 1, 2, 3]

note

O(1)

Overrides

AsyncStream.prepend, AsyncStreamBase.prepend

reduce

Applies the given (Async)Reducer to each element in the AsyncStream, and returns the final result.

Definition

reduce<const S extends AsyncReducer.CombineShape<T>>(shape: S & AsyncReducer.CombineShape<T>): Promise<AsyncReducer.CombineResult<S>>;

Type parameters

Name	Constraints	Description
S	AsyncReducer.CombineShape<T>

Parameters

Name	Type	Description
shape	S & AsyncReducer.CombineShape<T>

example

console.log(await AsyncStream.of(1, 2, 4).reduce(Reducer.sum))
// => 7
console.log(await AsyncStream.of(1, 2, 4).reduce(Reducer.product))
// => 8

Overrides

AsyncStream.reduce, AsyncStreamBase.reduce

reduceStream

Returns an AsyncStream where the given AsyncReducer is applied to each element in the stream.

Definition

reduceStream<const S extends AsyncReducer.CombineShape<T>>(shape: S & AsyncReducer.CombineShape<T>): AsyncStream<AsyncReducer.CombineResult<S>>;

Type parameters

Name	Constraints	Description
S	AsyncReducer.CombineShape<T>

Parameters

Name	Type	Description
shape	S & AsyncReducer.CombineShape<T>

example

console.log(
await AsyncStream.of(1, 2, 4)
.reduceStream(Reducer.sum)
.toArray()
)
// => [1, 3, 7]
console.log(
await AsyncStream.of(1, 2, 4)
.reduce(Reducer.product)
.toArray()
)
// => [1, 2, 8]

Overrides

AsyncStream.reduceStream, AsyncStreamBase.reduceStream

repeat

Returns an AsyncStream that returns the elements from this stream given amount of times.

Definition

repeat(amount?: number): AsyncStream<T>;

Parameters

Name	Type	Description
amount	number

example

const source = AsyncStream.of(1, 2, 3)
source.repeat()              // => AsyncStream(1, 2, 3, 1, 2, 3, 1, 2, ...)
await source.repeat(1).toArray()   // => [1, 2, 3]
await source.repeat(3).toArray()   // => [1, 2, 3, 1, 2, 3, 1, 2, 3]
await source.repeat(-3).toArray()  // => [1, 2, 3]

note

amount = undefined means that the AsyncStream is repeated indefintely @note amount = 1 means that the Stream is not repeated @note amount < 1 will be normalized to amount = 1 @note O(1)

Overrides

AsyncStream.repeat, AsyncStreamBase.repeat

single

Returns the first element of the Stream if it only has one element, or a fallback value if the Stream does not have exactly one value.

Definition

single<O>(otherwise?: AsyncOptLazy<O>): Promise<T | O>;

Type parameters

Name	Description
O

Parameters

Name	Type	Description
otherwise	AsyncOptLazy<O>

example

await AsyncStream.empty<number>().single()  // => undefined
await AsyncStream.of(1, 2, 3).single()      // => undefined
await AsyncStream.of(1).single()            // => 1
await AsyncStream.of(1, 2, 3).single(0)     // => 0

Overrides

AsyncStream.single, AsyncStreamBase.single

some

Returns true if any element of the AsyncStream satifies given pred function.

Definition

some(pred: (value: T, index: number) => MaybePromise<boolean>, options?: {
    negate?: boolean;
  }): Promise<boolean>;

Parameters

Name	Type	Description
pred	(value: T, index: number) => MaybePromise<boolean>
options	{     negate?: boolean;   }

example

await AsyncStream.of(1, 2, 3).some((v, i) => v + i > 10) // => false
await AsyncStream.of(1, 2, 3).some(async (v, i) => v + i > 1)  // => true

note

O(N)

Overrides

AsyncStream.some, AsyncStreamBase.some

splitOn

Returns an AsyncStream of collections of stream elements, where each array is filled with elements of this stream up to the next element that equals given sepElem according to the given eq function.

Definition

splitOn<R>(sepElem: T, options?: {
    eq?: Eq<T> | undefined;
    negate?: boolean | undefined;
    collector?: AsyncReducer.Accept<T, R> | undefined;
  }): AsyncStream<R>;

Type parameters

Name	Description
R

Parameters

Name	Type	Description
sepElem	T
options	{     eq?: Eq<T> | undefined;     negate?: boolean | undefined;     collector?: AsyncReducer.Accept<T, R> | undefined;   }

example

await AsyncStream.from('marmot').splitOn('m').toArray()  // => [[], ['a', 'r'], ['o', 't']]

note

O(1)

Overrides

AsyncStream.splitOn, AsyncStreamBase.splitOn

splitOnSlice

Returns an AsyncStream of collections of stream elements, where each array is filled with elements of this stream up to the next sequence of elements that matches given sepSeq ordered elements with the given eq function.

Definition

splitOnSlice<R>(sepSlice: AsyncStreamSource<T>, options?: {
    eq?: Eq<T> | undefined;
    collector?: AsyncReducer.Accept<T, R> | undefined;
  }): AsyncStream<R>;

Type parameters

Name	Description
R

Parameters

Name	Type	Description
sepSlice	AsyncStreamSource<T>
options	{     eq?: Eq<T> | undefined;     collector?: AsyncReducer.Accept<T, R> | undefined;   }

example

await AsyncStream.from('marmalade').splitSeq('ma').toArray()  // => [[], ['r'], ['l', 'a', 'd', 'e']]

note

O(1)

Overrides

AsyncStream.splitOnSlice, AsyncStreamBase.splitOnSlice

splitWhere

Returns an AsyncStream of collections of stream elements, where each array is filled with elements of this stream up to the next element that satisfies give function pred.

Definition

splitWhere<R>(pred: (value: T, index: number) => MaybePromise<boolean>, options?: {
    negate?: boolean | undefined;
    collector?: AsyncReducer.Accept<T, R> | undefined;
  }): AsyncStream<R>;

Type parameters

Name	Description
R

Parameters

Name	Type	Description
pred	(value: T, index: number) => MaybePromise<boolean>
options	{     negate?: boolean | undefined;     collector?: AsyncReducer.Accept<T, R> | undefined;   }

example

await AsyncStream.of(1, 2, 3, 4).splitWhere(async v => v == 3).toArray()
// => [[1, 2], [4]]

note

O(1)

Overrides

AsyncStream.splitWhere, AsyncStreamBase.splitWhere

take

Returns an AsyncStream that contains the elements of this stream up to a maximum of amount elements.

Definition

take(amount: number): AsyncStream<T>;

Parameters

Name	Type	Description
amount	number

example

await AsyncStream.of(1, 2, 3).take(2).toArray()   // => [1, 2]

note

O(N)

Overrides

AsyncStream.take, AsyncStreamBase.take

takeWhile

Returns an AsyncStream that contains the elements of this stream up to the first element that does not satisfy given pred function.

Definition

takeWhile(pred: (value: T, index: number) => MaybePromise<boolean>, options?: {
    negate?: boolean;
  }): AsyncStream<T>;

Parameters

Name	Type	Description
pred	(value: T, index: number) => MaybePromise<boolean>
options	{     negate?: boolean;   }

example

await AsyncStream.of(1, 2, 3).takeWhile(async v => v < 3).toArray()
// => [1, 2]

note

O(N)

Overrides

AsyncStream.takeWhile, AsyncStreamBase.takeWhile

toArray

Returns an Array containing all elements in the AsyncStream.

Definition

toArray(): Promise<T[]>;

example

await AsyncStream.of(1, 2, 3).toArray()   // => [1, 2, 3]

Overrides

AsyncStream.toArray, AsyncStreamBase.toArray

toJSON

Returns a JSON representation of the AsyncStream.

Definition

toJSON(): Promise<ToJSON<T[], 'AsyncStream'>>;

note

take care not to call on infinite Streams

example

await AsyncStream.of(1, 2, 3).toJSON()   // => { dataType: 'AsyncStream', value: [1, 2, 3] }

Overrides

AsyncStream.toJSON, AsyncStreamBase.toJSON

toString

Returns a string representation of the AsyncStream.

Definition

toString(): string;

note

to avoid issues with potentially infinite stream, this method does not list the stream elements. To do this, use join.

example

AsyncStream.of(1, 2, 3).toString()   // => 'AsyncStream(...<potentially empty>)'

Overrides

AsyncStream.toString, AsyncStreamBase.toString

transform

Returns an AsyncStream consisting of the concatenation of AsyncStreamSource elements resulting from applying the given reducer to each element.

Definition

transform<R>(transformer: AsyncTransformer.Accept<T, R>): AsyncStream<R>;

Type parameters

Name	Description
R

Parameters

Name	Type	Description
transformer	AsyncTransformer.Accept<T, R>

note

O(1)

example

await AsyncStream.of(1, 2, 3, 4, 5, 6).transform(AsyncTransformer.window(3)).toArray()
// => [[1, 2, 3], [4, 5, 6]]

Overrides

AsyncStream.transform, AsyncStreamBase.transform

window

Returns an AsyncStream containing windows of windowSize consecutive elements of the source stream, with each window starting skipAmount elements after the previous one.

Definition

window<R>(windowSize: number, options?: {
    skipAmount?: number | undefined;
    collector?: AsyncReducer.Accept<T, R> | undefined;
  }): AsyncStream<R>;

Type parameters

Name	Description
R

Parameters

Name	Type	Description
windowSize	number
options	{     skipAmount?: number | undefined;     collector?: AsyncReducer.Accept<T, R> | undefined;   }

example

await Stream.of(1, 2, 3, 4, 5, 6, 7).window(3).toArray()
// => [[1, 2, 3], [4, 5, 6]]
await Stream.of(1, 2, 3, 4, 5).window(3, 1).toArray()
// => [[1, 2, 3], [2, 3, 4], [3, 4, 5]]
await Stream.of(1, 2, 3, 4).window(2, 2, AsyncReducer.toJSSet()).toArray()
// => [Set(1, 2), Set(3, 4)]

Overrides

AsyncStream.window, AsyncStreamBase.window

withOnly

Returns an AsyncStream containing only those elements that are in the given values array.

Definition

withOnly<F extends T>(values: F[]): AsyncStream<F>;

Type parameters

Name	Constraints	Description
F	T

Parameters

Name	Type	Description
values	F[]

Overrides

AsyncStream.withOnly, AsyncStreamBase.withOnly

without

Returns an AsyncStream containing all elements except the elements in the given values array.

Definition

without<F extends T>(values: F[]): any;

Type parameters

Name	Constraints	Description
F	T

Parameters

Name	Type	Description
values	F[]

Overrides

AsyncStream.without, AsyncStreamBase.without